1. Field of the Invention
The present invention relates to a method for producing a koji of a hot pepper paste (called “gochujang” in Korea) with reduced hotness, a koji produced by the method, and a hot pepper paste prepared from the koji. More particularly, the present invention relates to a method for removing ingredients which cause hotness in traditional hot pepper pastes(Gochujang) while maintaining intrinsic colors of traditional hot pepper pastes(Gochujang), a koji produced by the method, and a hot pepper paste prepared from the koji.
2. Description of the Related Art
In general, hot pepper (botanical name: capsicum annuum L.) is a raw material for food spices, and widely used as a seasoning for hot pepper pastes(Gochujang), kimchi (Korean pickled vegetable), salted fishes, etc., in Korea. Hot pepper has occupied an important position in Korean dietary life. A main ingredient of hot pepper is capsaicin, which tastes hot. Capsaicin is a condensation product of 1-carboxylic acid having unsaturated aliphatic chain and vanillylamide. It is known that capsaicin analogues have a vanillylamine moiety to have hot taste, and exhibit maximum hotness when the acid moiety has 9 or 10 carbon atoms 1).
The capsaicin content of hot pepper varies depending on variations and growing districts of the hot pepper. By variations, there are, for example, paprika with no hotness and very hot habanero. Capsaicin is more abundant in the placenta of hot pepper than its pericarp and the seed.
Hot peppers produced in Cholla province, Korea, are smaller in size but have more capsaicin content than those produced in Chungchong province, Korea. The hot peppers produced in Chungchong province are large in size but have less hot taste. In addition, they have an excellent effect on coloring of hot pepper pastes. Hot peppers used for the preparation of kimchi and hot pepper pastes must meet various requirements, i.e. flavor, color, hotness, in this order. Recent consumer tastes have toward mildly hot taste. That is, hotness becomes less important, while color becomes more and more important.
Few efforts to develop novel variations reflecting this recent trend have been made. Even hot pepper paste-related industries make no effort to change the taste of hot pepper pastes toward mildness. Lee and Park reported that as the concentration of hot pepper powders in a koji increases (to 20%), titers of saccharifying amylase and protease considerably decrease 2). Woo and Kim's report suggested that since low titer of protease affects decomposition of protein during maturation, hot pepper powders must be added after decomposition by protein enzymes 3). These reports are limited to enzymatic activities according to the amount of hot pepper powders added.
Lee described in the report entitled [Effects of Meju (fermented soybeans) on capsaicin] that as a result of comparing loss in hotness according to the amount of capsaicin before and after fermentation of a hot pepper paste, the loss in hotness is mainly caused by enzymatic action 4). Lee et al. reported that A. niger, A. nidulans, etc., hydrolyze capsaicin and nonoylvanillylamide into N-vanillylcarbamoyl butyric acid through ω-hydroxylation, followed by β-oxidation. They introduced 30 species including 14 members of the genus Aspergillus undergoing the metabolic pathway discussed above, and further suggested potential 5 species 5). Ono et al. reported that Aspergillus strains (A. niger R-1 and A. oryzae R-2) decompose capsaicin using a koji extract to form vanillylamine or separate a fatty acid at the side chain of capsaicin, and particularly, A. niger R-1 converts vanillyl-n-nonoylamide to vanillyl amine and pelargonic acid 6).
In spite of results of the above-mentioned reports, no specific plans for efficiently utilizing the results have been established. Since enzymatic action for reducing hotness has been utilized only in the step of retting a hot pepper paste, there is a disadvantage in terms of low reduction of hotness.